Sleep speeds up post-viral healing
If you've been hit by a virus, you can speed up your healing process by making sure you get some good sleep. We deduce this from the results of an experiment that researchers at the University of Luebeck published in the Journal of Immunology. Sleep is crucial for the functioning of the immune system.
The researchers injected 27 young male students aged 26 with a vaccine against the virus that causes hepatitis A. The experiment lasted a year, and in week 0, 8 and 16 the men were given an injection.
Half of the men were allowed to sleep the night after the injection. The other half were not allowed to; they were allowed to read, listen to music, watch TV, but the researchers wouldn't allow the students to sleep.
Throughout the year the researchers monitored the subjects' blood. They noticed that during the course of the year the percentage of immune cells able to recognise the hepatitis A virus increased [CD40L+ HAV-specific Th-cells]. Through the Th cells the immune system can immediately eliminate the hepatitis A virus if it enters the body.
The researchers also noticed that the increase in CD40L+ HAV-specific Th-cells was twice as high in the men that had been allowed to sleep on the day they were vaccinated [black bars] than in the men that had been kept awake [white bars].
After the vaccination the number of antibodies in the blood that could recognise the hepatitis A virus increased [HAV-specific IgG1]. The antibodies recognise the hepatitis A virus and help to eliminate it. The concentration of the antibodies also increased more sharply in the men who had slept after their vaccination [curve with black circles] than in the men who had been kept awake [curve with white circles].
The researchers suspect that hormones play a key role in the immune-promoting effect of sleep. During your sleep you produce lots of growth hormone, and growth hormone has a stimulatory effect on the immune system. While you sleep the production of cortisol decreases, and cortisol inhibits the immune system. The researchers also believe that the sleep hormone melatonin plays a significant role.
A vaccine contains a weakened form of a pathogen. It doesn't make you ill, but the pathogen is strong enough to teach the immune system to recognise the real pathogen and how to fight it when there is a real attack. This learning process also takes place if you become properly ill, and this learning process probably also works better if you sleep well.
J Immunol. 2011 Jul 1;187(1):283-90.
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